On the existence of stationary states during granular compaction

TL;DR

This paper investigates the properties of stationary states in granular materials under gentle tapping, providing experimental evidence that these states are genuine thermodynamic states influenced by initial conditions and tapping protocols.

Contribution

It offers new experimental insights into the thermodynamic nature of stationary states in granular compaction and how they depend on initial conditions and tapping parameters.

Findings

Stationary states depend on tap characteristics and initial conditions.

Compactivity of packings is quantitatively determined.

Results support the thermodynamic interpretation of stationary states.

Abstract

When submitted to gentle mechanical taps a granular packing slowly compacts until it reaches a stationary state that depends on the tap characteristics. The properties of such stationary states are experimentally investigated. The influence of the initial state, taps properties and tapping protocol are studied. The compactivity of the packings is determinated. Our results strongly support the idea that the stationary states are genuine thermodynamic states.